This invention relates generally to valves usable to deliver water from housing or building plumbing lines. More particularly, it concerns improvements to such valves, simplifying their construction, and enhancing their performance.
There is need in such valves for improvements associated with blocking, or checking, back-flow where reverse flow pressure may build up. Also, there is need in such valves for disposing of built-up back flow pressure, as during checking or blocking of such back flow to the building plumbing. Such back flow, if unchecked, could contaminate water in that plumbing.
Existing hydrants rely on a plunger to engage a seat, to limit flow, by spring force alone. If the spring force is too strong it restricts flow; and if the spring force is too weak, or if the plunger is corroded into the housing, it will not or may not properly shut off on the seat. If the plunger does not effectively shut off on the seat (to act as a check valve), it will not prevent backflow, backsiphonage or relieve backpressure. Build-up of backpressure would or could disrupt use of a plastic hydrant outer tube or body. Also, existing hydrants might pass the ASSE 1019 requirements when new, but would likely fail the requirements after a short period of “infield use”. After three years it was found in a survey that about 68% of such hydrants failed to pass the ASSE 1019 tests.
There is need for improvements in hydrants as provided by the present invention; and wherein one or both of elongated outer and inner tubular body members consist of pressure expansible plastic material, in compact configuration, and are characterized by high reliability, absence of bore corrosion, and ease of installation and operation, and wherein an annular seal extends about an axis defined by a closure member, there being an axially elongated bore defined by the outer member, and into which the seal has sliding sealing fit as the inner member is advanced. There is particular need for improvements in hydrants that provide protection against freeze conditions.